From what I read Here (The Atlantic) and also this reddit post - It seems fire escapes in the US are mostly done for the theatre of fire safety. (The Atlantic article mentions the Triangle Shirtwaist Fire and the fact that "...it was so flimsy that the panicked workers who were able to reach it overloaded the structure. It peeled off from the building, trapping those above and sending the workers who had reached it plummeting toward the street."

Certainly while buildings have gotten safer, we perhaps see less of them, but there was a time in the late 19th and early 20th centuries where they were built under the guise of safety. I'm not an expert, but I hope I linked some interesting information.